Micro Electro Mechanical Systems (MEMS) resonators have been developed that can provide accurate clocking signals. However, the industry has been slow to adopt clock generators that include MEMS resonators because of uncertainty regarding reliability. Some of the uncertainty can be reduced by increased in-production and post-production testing. However, it is well known that failures in new products are often only discovered later in the life of a device, long after manufacture and initial testing. Such failures can sometimes be detected after installation but usually require that the appliance or system in which a device operates is taken out of operation for testing.
When a system fails as a result of a failure of a complex semiconductor device in it, Built-in Self Test (BIST), usually exercised at power-up, can be used to locate the failed device for replacement. However, the locating and replacing do not take place until the system fails, incurring the cost and inconvenience of a system shutdown.
In light of the above, a need exists for a MEMS clock generator that generates a reliable clock signal. A further need exists for a method for generating a reliable clock signal using an array of MEMS resonators. The method and apparatus of the present invention meets the above needs.